Hi,
Here's a patch against 2.5.3-pre1 for the USB hcd driver that removes a
workaround when unlinking periodic urbs in their completion handlers.
This patch was written by David Brownell.
thanks,
greg k-h
diff -Nru a/drivers/usb/hcd.c b/drivers/usb/hcd.c
--- a/drivers/usb/hcd.c Wed Jan 16 09:57:47 2002
+++ b/drivers/usb/hcd.c Wed Jan 16 09:57:47 2002
@@ -1081,20 +1081,20 @@
if (!urb)
return -EINVAL;
- // FIXME: add some explicit records to flag the
- // state where the URB is "in periodic completion".
- // Workaround is for driver to set the urb status
- // to "-EINPROGRESS", so it can get through here
- // and unlink from the completion handler.
-
/*
* we contend for urb->status with the hcd core,
* which changes it while returning the urb.
+ *
+ * Caller guaranteed that the urb pointer hasn't been freed, and
+ * that it was submitted. But as a rule it can't know whether or
+ * not it's already been unlinked ... so we respect the reversed
+ * lock sequence needed for the usb_hcd_giveback_urb() code paths
+ * (urb lock, then hcd_data_lock) in case some other CPU is now
+ * unlinking it.
*/
spin_lock_irqsave (&urb->lock, flags);
- if (!urb->hcpriv
- || urb->status != -EINPROGRESS
- || urb->transfer_flags & USB_TIMEOUT_KILLED) {
+ spin_lock (&hcd_data_lock);
+ if (!urb->hcpriv || urb->transfer_flags & USB_TIMEOUT_KILLED) {
retval = -EINVAL;
goto done;
}
@@ -1103,6 +1103,8 @@
retval = -ENODEV;
goto done;
}
+
+ /* giveback clears dev; non-null means it's linked at this level */
dev = urb->dev->hcpriv;
hcd = urb->dev->bus->hcpriv;
if (!dev || !hcd) {
@@ -1110,6 +1112,27 @@
goto done;
}
+ /* For non-periodic transfers, any status except -EINPROGRESS means
+ * the HCD has already started to unlink this URB from the hardware.
+ * In that case, there's no more work to do.
+ *
+ * For periodic transfers, this is the only way to trigger unlinking
+ * from the hardware. Since we (currently) overload urb->status to
+ * tell the driver to unlink, error status might get clobbered ...
+ * unless that transfer hasn't yet restarted. One such case is when
+ * the URB gets unlinked from its completion handler.
+ *
+ * FIXME use an URB_UNLINKED flag to match URB_TIMEOUT_KILLED
+ */
+ switch (usb_pipetype (urb->pipe)) {
+ case PIPE_CONTROL:
+ case PIPE_BULK:
+ if (urb->status != -EINPROGRESS) {
+ retval = 0;
+ goto done;
+ }
+ }
+
/* maybe set up to block on completion notification */
if ((urb->transfer_flags & USB_TIMEOUT_KILLED))
urb->status = -ETIMEDOUT;
@@ -1130,6 +1153,7 @@
/* asynchronous unlink */
urb->status = -ECONNRESET;
}
+ spin_unlock (&hcd_data_lock);
spin_unlock_irqrestore (&urb->lock, flags);
if (urb == (struct urb *) hcd->rh_timer.data) {
@@ -1154,6 +1178,7 @@
}
goto bye;
done:
+ spin_unlock (&hcd_data_lock);
spin_unlock_irqrestore (&urb->lock, flags);
bye:
if (retval)
_______________________________________________
[EMAIL PROTECTED]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
